Power-hammer.



W. GRAHAM. POWER HAMMER APPLICATION rum) PEB.1,1907.

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W. GRAHAM.

POWER HAMMER.

APPLICATION rum) r1113. 1, 1907.

936,31 Patefited Oct. 12, 1909.

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W. GRAHAM.

POWER HAMMER.

APPLICATION FILED FEB. 1, 1907.

936,316, Patented Oct. 12,1909.

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W. GRAHAM. POWER HAMMER. APPLICATION FILED FEB? 1, 1907.

Patented Oct. 12, 1909.

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WILLIAM GRAHAM, OF WESTMINSTER, LONDON, ENGLAND.

POWER-HAMMER.

Specification of Letters Patent.

Application filed February 1, 1907.

Patented Oct. 12, 1909. Serial No. 355,278.

To all whom it may concern:

Be it known that I, IVILLIAM GRAHAM, a subject of the King of GreatBritain and Ireland, and residing at 3 Rochester row, WVestminister,London, in the county of Middlesex, England, have invented certain newand useful Improvements in and Relating to Power-Hammers, of which thefol lowing is a specification.

This invention relates to improvements in those pneumatic power hammersin which the tup is raised wholly or partly by vacuum and forceddownward by pressure of air, the vacuum and air pressure being createdby means of a pump arranged in proximity to the tup chamber of thehammer.

The object of the present inventlon is to improve the action of thesehammers by causing the hammer to give a strong blow with a slight pauseon the work after the blow has been delivered. With a continuouslyrunning pump this has hitherto been impractlcable.

The present invention consists in a pneumatic power hammer driven by acontinuously running pump, and arranged to give hard blows on the anvilwith a pause at the end of the blow, whileat the same time the maximumefliciency is obtained from the compressing device.

The principle utilized 111 this lnvent on is that when a body ofcompressed a1r is admitt-ed to a chamber the pressure exerted by thatcompressed air is proportional to the size of the chamber and to theamount of compression.

In the construction employed herein the admission of compressed air fromthe pump to the hammer tup is delayed, so that some considerablepressure is obtained in the pump chamber at the time of admission, thiscompressed air being admitted to the hammer chamber when the tup is atthe top of its stroke, and therefore when the clearance space above thetupis smallest.

The invention also comprises additional means for delaying the liftingof the hammer tup by cutting OK the communication between the pump andthe tup chamber for a portion of the travel of the pump piston wherebythe end of the compression stroke is idle, and the beginning of theyacuum stroke is used for creating some considerable reduction ofpressure in the pump chamber before the passage from the pump to the tupchamber is again opened.

The invention also comprises a modification in which two passages areprovided between the pump and the hammer chamber, and both thesepassages may be controlled both automatically and by hand or foot, oneof the passages being arranged for passing the compressed air to thehammer chamher at the beginning of the downward stroke of the hammer,and only after a predetermined pressure has been created in the pump. Inthis modification the retarding of the admission of compressed air isobtained by means of a spring or the like controlling a non-returnvalve.

Referring now to the accompanying drawings :Figure 1 is a sideelevation; and Fig. 2 a vertical section of one modification of myinvention, in which the result herein aimed at is obtained by means of amechanically actuated shell valve, with an inner valve. Fig. 8 is asection of the shell valve in the same; while Figs. 4 and 5 are a planand section respectively of the inner valve. Fig. 6 shows in section amodification in which the result aimed at in the present invention isobtained by means of a spring controlled non-return valve; while Fig. 7is a side elevation of this modification.

According to the form shown in Figs. 1 to 5, a pump chamber, a, and atup chamber, Z), are arranged in an inverted position with theirextremities in proximity. The upper ends of the two chambers areconnected by a passage, 0, in which there is provided a shell valve, 6,operated mechanically from the cam, h, Fig. 1, through links, 9 and f.Within the valve, 6, there is provided another valve, (Z, operated byhand through the crank and links 0 and g, or by foot through the crank,a, upper and lower link, 0, and treadle, 79. The valve, (Z, is seen inFigs. 4 and 5, Fig. 5 being a section on the line A B of Fig. 4c. Thesegmental part, it, extends between two circular end disks, and isprovided with perforations, Z, while an extension is provided on oneside for attachment to the crank, 02.

A trunk end, 8, on the piston, r, is adapted to enter a recess, 2,,provided in the cover for the purpose hereinafter explained, while apassage, 11, in the cylinder, port w, in the piston and non-returnvalve, a, are provided to permit of the escape of air from the annularspace after said trunk has entered the recess, 25', in the cylinder. I

The operation of this device is as follows :Assu1ne the tup, y, restingon the anvil as shown. When the pump piston travels downward nosubstantial vacuum is created in the tup chamber until the trunk, 8,passes out from the recess, 2?. During this time cam, h, operates thelinks to open the shell valve, 6, into the position shown, the raisedpart of the cam representing the closed position of the valve, whilethe. lower part represents the open position. When the trunk, 8, passesfrom the recess, t, the higlrvacuum which obtains in the annular spacearound the trunk is communicated to the tup cham ber, Z), and the upwardstroke of the tup quickly takes place. At or near the end of the suctionstroke, when the crank is about the position X, Fig. 2 the lever, g,rises on to the high part of the cam, h, and thereby closes the shellvalve, 0. As shown in F 1g. 1, this high part of the cam extends for aconsiderable angle, thereby causing a considerable part of the returnstroke of the pump to be completed before the valve, 6, is again open.There is thus a considerable pressure created in the pump chamber and asthe opening of the valve, 6, is effected rapidly when the crank reachesthe position, Y, this pressure is quickly communicated to the tupchamber. As the tup is at the top of its stroke, the reduction ofpressure in the air after the opening of the valve is comparativelysmall, so that practically the full compression pressure of the pump istransmitted to the tup and utilized for the purpose of adding force tothe blow. Shortly after this impact of airhas been transmitted to thetup, the trunk, s, enters the recess, t, and the cycle of operationsstarts once more.

By adjusting the position of the inner valve, (Z, which is provided witha flexible non-return valve, m, or the like, the action of the hammermay be readily controlled in the manner now well known as applied topneumatic power hammers, and no further description of this isnecessary.

According to the modification of this invention illustrated in Figs. (3and 7, I dis- I the tup chamber, Z).

the end of the pump piston and chamber. The valve, 5, under the actionof spring, 6, only opens when the pressure within the pump chamber isconsiderable. In this form the delay or pause of thetup on the anvilmay' be lengthened by providing a spring on the valve, 3, so as to causethat valve to open only when a considerable vacuum obtains in the pump.This, however, is not essential. A hand or foot operated valve, 4, isprovided in the passage, 2, for effecting control of the hammer, thisvalve being preferably articulated to the valve, 3. When the valve 5opens the pressure of air acts upon a piston 7 against a spring (5 andthereby prevents the valve 5 acting as a reducing valve.

It will be seen that in the form described with reference to Figs. 1 to5, the delay in the admission of the air to the cylinder is effected bya positive motion of the valve while in the second describedmodification spring control is used for effecting the delay.

The improvements according to the present invention may be readilyapplied especially in the form shown in Figs. 6 and 7 to those pneumatichammers which are actuated by means of a double acting pump, and I wishit to be understood that such a form is included within the terms oftheclaims. In such double acting hammers the downstroke of the pump isgenerally the lifting stroke, and therefore corresponds to the down orsuction stroke, in the forms of the invention illustrated in theaccompanying drawings.

Having now described my invention what I claim as new and desire tosecure by Letters Patent is 1. A pneumatic hammer having in combinationa tup and tup chamber, a reciprocating pump working in a separate pumpchamber, connecting means between said pump and tup chambers, means forclosing said connecting means, and means acting automatically to cause alag between said pump andtup pistons after a blow has been struck untllthe pump piston has moved outward a predetermined portion of its stroke.

2. A pneumatic hammer having in combination, a tup and tup chamber, areciprocating pump in proximity to said tup chamber, a connectionbetween the ends of said pump and tup chamber, a mechanically operatedported shell valve in said connection, a nonreturn valve working withinsaid shell valve, substantially as and for the purposes hereinbeforedescribed.

3. A pneumatic hammer having in combination a tup and tup chamber, areciprocating pump in proximity to said chamber, a

rotating cranked shaft operating said pump, a cam on said shaft, aconnection between the ends of said pump and tup chamber, a ported shellvalve operated mechanically from the said cam, a non-return valve withinsaid shell valve, substantially as described.

4. A pneumatic hammer having in combination a tup and tup chamber, areciprocating pump in proximity to said tup chamber, a rotating crankedshaft driving said pump, a cam, h, on said shaft, a connection betweenthe ends of said pump and tup chamber, a cylindrical port-ed shell valvein said connection links 9 and f, arranged to transmit motion from cam,h, to the shell valve, a nonreturn valve working within said portedshell valve and means for rotating said nonreturn valve for the purposeof manually controlling the operation of the hammer, substantially asdescribed.

5. In a pneumatic hammer having its tup operated directly by areciprocating pump and a passage between said pump and tup chamber,automatic means for delaying the lifting of the tup after a blow hasbeen struck, comprising trunk, s, on the pump piston, a chamber, t, onthe pump cover with which said pump is arranged to co-act.

6. A pneumatic hammer having in combination a tup and tup chambercontinuously working a reciprocating pump in proximity to said tupchamber and a passage connecting said pump and tup chamber, automaticmeans for delaying the lifting of the tup after a blow has been struck,comprising a trunk, s, on the pump piston, a chamber, t, on a pump coverwith which said trunk, s, engages for the later part of the compressionstroke, a relief duct, 4), arranged to permit the escape of airimprisoned behind the pump piston after the trunk, 8, has engaged withthe recess, t.

In testimony whereof, I aflix my signature in presence of two witnesses.v

WILLIAM GRAHAM.

Witnesses:

ALBERT E. PARKER, FRANCIS J. BIGNELL.

